Patent GB-190618956-A (GB)
Title: Improvements in and relating to Alternating Electric Current Motors and in Systems of Operating andd Controlling same.
Filed: 1906-08-24
Granted: 1907-08-24
Abstract: 18,956. British Thomson-Houston Co., [General Electric Co.]. Aug. 24. Switches.-In a system of control of induction motors in which polyphase motors are supplied with current from a phase-changer constructed as an induction motor and energized with single-phase current, two induction motors having different pole numbers are provided, and alternately used as phase-changer and motor, the windings of the motor when acting as a phase-changer being so connected together as to give balanced polyphase voltages under load ; a third motor may ba connected in cascade with either of the first two. In the application of the invention to a single-phase locomotive, three motors M', M<2>, M<3>, Fig. 1, are mounted on separate axles, and the driving-wheels B are provided with cornecting-rods b. The motors M', M'are sleeved on their axles, and provided with magnetic clutches C<1>, C<2>, while the motor M<3> is fast on its axle. With the motor M' arranged for four poles, and each of the motors M<2>, M<3> for eight poles, three different speeds are obtained corresponding to sixteen, twelve, and eight poles, the first and second speeds being obtained with the motors M', M<2> as phase-changers respectively and the two remaining motors connected in cascade, and the third speed with the motor M<1> as phasechanger and the other motors connected in parallel. With the speed controlling switch E, Fig. 2, in its first position 1<x>, and the starting and reversing switch D and the switch. F mechanically coupled. thereto also in their first positions, the motor m is short-circuited, the clutches C<1>, C<2>, as well as the motors M<2> M<3>, are open-circuited, and the primary M' excited from the trolley T through a resistance R and inductances I. When the motor M<1> has run up to speed, the starting switch D is moved into its second position, so that the terminal 1 of the motor M' is connected direct to the trolley T, the terminal 8 is open-circuited, and the motor M' runs as a single-phase motor, producing its own rotating field which induces polyphase voltages at the terminals of the primary windings. With the switch E in its first running position 2<x>, the connexions shown in Fig. 7 are obtained, the motor M<2> being connected in cascade with the motor M<3> and supplied with current from the phase-changer M', the terminal 5 of the phase 5-7 being connected to an intermediate terminal 2 of the phase 1-3, so as to obtain, under load, balanced polyphase voltages at the terminals 1, 7, 8. When the switch E is in its second running position 3x, the clutch C' is closed, and the clutch C<2> is opened and the motor M<2> run as a phase-changer with the terminal 15 connected to the terminal 12. The rotor m<1> is connected in cascade with the motor M3, and is supplied with current from the phase-changer M<2>. In the third running position 4x, the motor M<1> again becomes the phase-changer, and the motors M<2>, M3 are connected in parallel. To operate in the reverse direction, the switch E is returned to its off-position 1<x>, and the switches D, F moved in the opposite direction from their off-position, and instead of the terminal 5 being connected to the terminal 2 when M' is the phase - changer, the terminal 4 is connected to the terminal 6, a corresponding change being made in the connexions of the motor M<2> when used as the phase-changer.